Promotion of corneal epithelial wound healing in diabetic rats by the combination of a substance P-derived peptide (FGLM-NH2) and insulin-like growth factor-1

Aims/hypothesis. The healing of corneal epithelial wounds is often delayed in individuals with diabetes. The effect of the combination of a substance P-derived tetrapeptide (phenylalanine-glycine-leucine-methionine amide, or FGLM-NH2) and insulin-like growth factor-1 (IGF-1) on corneal epithelial wound healing was investigated in rats with streptozotocin-induced diabetes. Methods. The corneal epithelium of diabetic and non-diabetic rats was removed, and the animals were treated by the application of eye drops containing FGLM-NH2 and IGF-1, or vehicle alone as a control, six times a day for 3 days. The area of the corneal epithelial wound was measured at various times up to 72 h after removal of the corneal epithelium. Results. The rate of corneal epithelial wound healing was slower in diabetic rats treated with vehicle than in non-diabetic rats. However, the rate of wound closure in diabetic rats treated with FGLM-NH2 and IGF-1 was markedly increased compared with that in diabetic rats treated with vehicle. The wound healing process seemed similar in normal rats and in diabetic rats treated with FGLM-NH2 and IGF-1. Conclusion/interpretation. The combination of FGLM-NH2 and IGF-1 promotes corneal epithelial wound healing in diabetic rats, suggesting that such a treatment might prove effective in humans with diabetic keratopathy.